ABSTRACT: Sugar sweetened beverages (SSBs) are a common risk factor for tooth decay (Early Childhood Caries, ECC) and obesity. Both are serious problems; particularly for Latino children, as they are more likely to drink SSBs and less likely to drink water. Our primary aim is to test the efficacy of home delivery of water bottles with family-based parental counseling on relapse of ECC, weight gain and SSB consumption compared to usual care (parent health nutrition education). Our secondary aim is to investigate the mechanism of action of the intervention on sugar consumption, caries relapse and weight gain through analysis of mediators, moderators and confounders. Our rationale is that families lack the capability (skills, self-efficacy) and opportunities (child-friendly water bottles, social support), but are motivated to reduce SSB consumption, particularly after dental treatment under general anethesia. Our oral health goal is to slow the rate of relapse of ECC so that teeth can exfoliate normally or allow for time for the child to develop coping skills for less-costly in- office dental treatments without sedation. ECC impacts quality of life, causes pain, eating and sleeping problems. The care standard of surgical care under general anesthesia fails to address the cause of ECC, and the disease frequently relapses. In addition, hospitalization and general anesthesia divert scarce treatment resources away from public health efforts to prevent the ravages of the disease. Drinking water instead of SSBs can reduce children's total daily sugar intake thereby reduce both ECC and obesity. METHODS: 260 children (age < 9 years, 50% Latino) who had treatment for ECC under general anesthesia and their families will be randomly assigned to the experimental intervention or usual care (nutrition health education). Participants in the intervention will have fluoridated water in cute brightly-colored animal- shaped bottles delivered bi-weekly for one year to their homes coupled with family-directed, monthly caregiver counseling provided by bilingual dietitians to support implementing change in beverage consumption. The intervention employs established behavioral change techniques shown to impact dietary change in young children: environmental and social opportunities and caregivers' stimulus control, prompt identification as role model and self-regulation. The primary outcome is time to onset of new dental caries lesions through two years. Secondary outcomes are body mass index for age (BMI-for-age) and SSB consumption. SIGNIFICANCE: This study will provide the best evidence to date of whether changing the home environment and empowering families can promote water intake, in lieu of sugar sweetened beverages, to reduce ECC and obesity in children. We address gaps in knowledge in nutrition in the home and theory on means to change dietary habits. The proposal for research is a unique multidisciplinary collaboration between University of Washington and the Yakima Valley Farm Workers Clinic serving immigrant Latino families. The results will serve as a step toward trials to generalize findings and scale-up effective interventions.